Radio access schemes and radio networks (hereinafter referred to as “Long Term Evolution (LTE)” or “Evolved Universal Terrestrial Radio Access (EUTRA)”) of cellular mobile communication have been examined in 3rd Generation Partnership Project (3GPP). In LTE, a base station device is also referred to as an evolved NodeB (eNodeB) and a mobile station device is also referred to as user equipment (UE). LTE is a cellular communication system in which a plurality of areas covered by base station devices are arranged in cell shapes. A single base station device may manage a plurality of cells.
LTE corresponds to time division duplex (TDD). LTE adopting a TDD scheme is referred to as TD-LTE or LTE TDD. TDD is a technology for enabling full duplex communication in a single frequency band by performing time division multiplexing on an uplink signal and a downlink signal.
In 3GPP, a traffic adaptation technology and an interference reduction technology (DL-UL Interference Management and Traffic Adaptation) which are applied to TD-LTE has been examined. A traffic adaptation technology is a technology for changing ratios of uplink resources to downlink resources according to uplink traffics and downlink traffics. The traffic adaptation technology is also referred to as a dynamic TDD.
NPL 1 proposes a method of using flexible subframes as a method of realizing traffic adaptation. A base station device can transmit downlink signals or can receive uplink signals with flexible subframes. In NPL 1, a mobile station device regards flexible subframes as downlink subframes unless the mobile station device is instructed to transmit uplink signals in a flexible subframe by the base station device.
NPL 1 describes that a hybrid automatic repeat request (HARQ) timing corresponding to a physical downlink shared channel (PDSCH) is decided based on a newly introduced uplink-downlink configuration (UL-DL configuration) and an HARQ timing corresponding to a physical uplink shared channel (PUSCH) is decided based on a first UL-DL configuration.
NPL 2 describes that (a) an UL/DL Reference Configuration is introduced and (b) several subframes can be scheduled for either uplink or downlink in accordance with dynamic grant/assignment from a scheduler.
In NPL 3, section 7.2 describes a procedure of mobile station devices to report channel state information (CSI). A base station device allocates downlink resources to the mobile station devices based on the channel state information reported from the plurality of mobile station devices. The channel state information includes a channel quality indicator (CQI).